Add Pubstack bidder documentation (#1) (prebid#6438)

* Add Pubstack bidder documentation (#1)

* Add Pubstack bidder documentation page

* Enhance Pubstack bidder adapter documentation

Updated Pubstack bidder documentation with new fields and types.

* Update Pubstack bidder documentation with new fields

* Update dev-docs/bidders/pubstack.md

Co-authored-by: Muki Seiler <muuki88@users.noreply.github.com>

* Update dev-docs/bidders/pubstack.md

Co-authored-by: Muki Seiler <muuki88@users.noreply.github.com>

---------

Co-authored-by: Muki Seiler <muuki88@users.noreply.github.com>

Author: gpolaert

dev-docs/bidders/pubstack.md

@@ -0,0 +1,81 @@
+---
+layout: bidder
+title: Pubstack
+description: Prebid Pubstack Bidder Adapter
+biddercode: pubstack
+prebid_member: true
+pbjs: true
+pbs: true
+gvl_id: 1408
+media_types: banner, video, native
+multiformat_supported: will-bid-on-any
+tcfeu_supported: true
+usp_supported: true
+gpp_sids: tcfeu, tcfca, usnat, usstate_all, usp
+coppa_supported: true
+userId: all
+schain_supported: true
+dchain_supported: true
+fpd_supported: true
+floors_supported: true
+deals_supported: true
+safeframes_ok: true
+privacy_sandbox: paapi, topics
+ortb_blocking_supported: true
+sidebarType: 1
+---
+
+### Integration Note
+
+The Pubstack bidding adapter requires setup and approval before use. Contact your Pubstack account team to enable production traffic.
+
+### Bid Params
+
+{: .table .table-bordered .table-striped }
+
+| Name | Scope | Description | Example | Type |
+| --- | --- | --- | --- | --- |
+| `siteId` | required | Pubstack site identifier. | `'example-site-id'` | `string \| uuid` |
+| `adUnitName` | required | Pubstack ad unit name associated with the placement. | `'homepage-top-banner'` | `string` |
+
+### Test Parameters
+
+```javascript
+var adUnits = [
+  {
+    code: 'test-div-1',
+    mediaTypes: {
+      banner: {
+        sizes: [[300, 250]]
+      }
+    },
+    bids: [
+      {
+        bidder: 'pubstack',
+        params: {
+          siteId: 'example-site-id',
+          adUnitName: 'homepage-top-banner'
+        }
+      }
+    ]
+  },
+  {
+    code: 'test-video-div',
+    mediaTypes: {
+      video: {
+        playerSize: [[640, 360]],
+        context: 'outstream'
+      }
+    },
+    bids: [
+      {
+        bidder: 'pubstack',
+        params: {
+          siteId: 'example-site-id',
+          adUnitName: 'article-video-slot'
+        }
+      }
+    ]
+  }
+];
+```